The Effects of Transcranial Direct Current Stimulation (tDCS) on Working Memory Training in Healthy Young Adults

Abstract

Working memory (WM) is a fundamental cognitive ability to support complex thought, but it is limited in capacity. WM training has shown the potential benefit for those in need of a higher WM ability. Many studies have shown the potential of transcranial direct current stimulation (tDCS) to transiently enhance WM performance by delivering a low current to the brain cortex of interest, via electrodes on the scalp. tDCS has also been revealed as a promising intervention to augment WM training in a few studies. However, those few tDCS-paired WM training studies, focused more on the effect of tDCS on WM enhancement and its transferability after training and paid less attention to the variation of cognitive performance during the training procedure. The current study attempted to explore the effect of tDCS on the variation of performance, during WM training, in healthy young adults. All the participants received WM training with the load-adaptive verbal N-back task, for 5 days. During the training procedure, active/sham anodal high-definition tDCS (HD-tDCS) was used to stimulate the left dorsolateral prefrontal cortex (DLPFC). To examine the training effect, pre- and post-tests were performed, respectively, 1 day before and after the training sessions. At the beginning of each training session, stable-load WM tasks were performed, to examine the performance variation during training. Compared to the sham stimulation, higher learning rates of performance metrics during the training procedure were found when WM training was combined with active anodal HD-tDCS. The performance improvements (post–pre) of the active group, were also found to be higher than those of the sham group and were transferred to a similar untrained WM task. Further analysis revealed a negative relationship between the training improvements and the baseline performance. These findings show the potential that tDCS may be leveraged as an intervention to facilitate WM training, for those in need of a higher WM ability.

Anodal and cathodal tDCS modulate neural activity and selectively affect GABA and glutamate syntheses in the visual cortex of cats

“…Transcranial direct current stimulation (tDCS) is a non-invasive tool that can reversibly modulate brain activity by applying a weak, constant direct current through the scalp or skull (Nitsche & Paulus, 2000;Dimov et al 2016;Zmigrod et al 2016;Mosayebi Samani et al 2019). Accumulating evidence has demonstrated that polarity-specific tDCS can improve motor performance (Amadi et al 2015;Karok et al 2016), modulate cognitive or perceptual function (Spiegel et al 2012;Spiegel et al 2013;Labbe et al 2016;Price et al 2016;Rosen et al 2016;Weigl et al 2016;Zmigrod et al 2016;Bruckner & Kammer, 2017;Hertenstein et al 2019;Wiegand et al 2019;Xiong et al 2019;Salvi et al 2020), and facilitate learning and memory (Choe et al 2016;Sandrini et al 2016;Van Meel et al 2016;Ke et al 2019;Nissim et al 2019;Gibson et al 2020). Clinical studies showed that tDCS is a potential therapeutic tool for some neurological or psychiatric disorders (Yoon et al 2012;Zobeiri & van Luijtelaar, 2013;Assenza et al 2014;Dhamne et al 2015;Ding et al 2016;Kang et al 2019;Strumila et al 2019;Vigod et al 2019;Cosentino et al 2020;McClintock et al 2020).…”

Tracking Changes in Frontal Lobe Hemodynamic Response in Individual Adults With Developmental Language Disorder Following HD tDCS Enhanced Phonological Working Memory Training: An fNIRS Feasibility Study

“…In tDCS studies, training typically includes multiple sessions ( Au et al, 2016 ; Ruf et al, 2017 ; Ke et al, 2019 ). For example the participants in Ruf et al (2017) received tDCS stimulation concurrent with working memory training over a period of three training sessions whereas the participants in Richmond et al (2014) tDCS enhanced working memory training over a period of 10 training sessions.…”

Dynamic switching between intrinsic and extrinsic mode networks as demands change from passive to active processing

“…The conjunction analysis revealed that also other areas activated during ON-blocks were found for the angular gyrus, superior parietal lobule, anterior insula, and middle frontal gyrus. All these regions are implicated in higher-order cognition, including mental arithmetic, visuo-spatial processing, mental rotation and working memory 27,[42][43][44] . In addition, the occipital activation which most likely reflects the fact that the tasks were all visual in nature.…”